Illuminated liquid level indicator

Abstract

A liquid level indicator indicates liquid level in a standpipe with a color change in a column of lights positioned alongside the standpipe. The indicator can be used alongside a mechanical indicator which indicates liquid level in a standpipe with a color change in a column of magnetic elements to light the mechanical indicator. The two indicators when used together provide high visibility under all conditions.

What is claimed is: 
     
       1. A liquid level indicator comprising
 a first elongated frame having a channel-shaped cross-section and formed from a nonmagnetic material and a bottom wall; 
 a plurality of closely-spaced parallel magnetic slats pivotally mounted in the frame and extending across the channel, each of said slats having a first face of a first color and an oppositely-facing second face of a second color; 
 a second longitudinally elongated channel shaped frame formed of a nonmagnetic material, the second frame comprising a first sidewall, a second sidewall parallel to the first sidewall, and a bottom wall connecting a bottom end of the first sidewall with a bottom end of the second sidewall, the second frame having a longitudinal axis and further comprising a mounting wall positioned parallel to the bottom wall which mounts the second frame to the first frame; 
 an elongated generally rectangular circuit board mounted inside of the channel of the second frame, 
 said circuit board carrying a plurality of bi-color LED assemblies and a like plurality of hall effect switches operably associated with the plurality of bi-color LED assemblies, said plurality of hall effect switches being spaced apart from each other by a distance equal to the center-to-center spacing between the parallel magnetic slats and said plurality of bi-color LED assemblies being spaced apart from each other by a distance equal to the center-to-center spacing between the parallel magnetic slats, said bicolor LED assemblies being positioned and oriented to directly light the slats, one LED assembly per slat, said hall effect switches being positioned and oriented to sense a magnetic field passing close to each slat at a location behind the bottom wall of the first frame and operably associated with a bi-color LED assembly to change the emitted LED color lighting the slat when the magnetic field is sensed. 
 
     
     
       2. A liquid level indicator as in  claim 1  wherein
 the first elongated frame comprises a longitudinally elongated channel shaped frame formed of a nonmagnetic material and defined by a first sidewall, a second sidewall parallel to the first sidewall, and a bottom wall connecting a bottom end of the first sidewall with a bottom end of the second sidewall, said elongated channel shaped frame having a longitudinal axis; 
 said liquid level indicator further comprising a plurality of parallel pins extending from the first sidewall to the second sidewall, said parallel pins being positioned parallel to the bottom wall and longitudinally spaced apart from each other and the bottom wall and extending normally to the longitudinal axis of the frame; 
 wherein the plurality of closely-spaced parallel magnetic slats are pivotally mounted to the parallel pins, one slat per pin, each said magnetic slat having a thickness, a height which is greater than the thickness, and a length which is greater than the height, and being positioned on a pin with its length extending parallel to the pin for pivoting movement around the pin and its height extending parallel to the longitudinal axis of the frame, each of the plurality of magnetic slats having a magnetic axis parallel to its height, a first face having a first color, and an opposite second face having a second color which is optically discernable from the first face; 
 wherein the plurality of parallel pins are spaced apart a first distance which is slightly greater than the height of the slats, so that adjacent slats are aligned with each other in an edge to edge relationship due to mutual magnetic attraction and have sufficient clearance therebetween to permit each slat to pivot without mechanical interference from adjacent slats; and 
 each slat has a length which is at least three times its height to facilitate viewing of the slat face; 
 said apparatus further comprising 
 a tube; 
 a float positioned within the tube; and 
 a magnet positioned within the float; 
 wherein the first channel is mounted to the tube so that the slats are pivotable by the action of the magnet in the float and the hall effect switches sense the magnet in the float as the float passes by it's closest point to the switch. 
 
     
     
       3. A liquid level indicator as in  claim 2  having an upper end and a lower end and further comprising
 a lowermost hall-effect switch/bi-color LED assembly pair on the board, 
 a lowermost electrical circuit extending between the pair, 
 a lowermost multiple input AND gate device positioned in the lowermost electrical circuit; said lower-most multiple-input AND gate device receiving a single input from it's associated hall effect switch and it's remaining inputs from additional AND gate devices positioned in electrical circuits extending between hall-effect switches and bi-color LED assemblies serially above the lower-most AND gate device, 
 wherein an AND gate device output from matched inputs is a high voltage signal and an AND gate device output from mismatched inputs is a low voltage signal, 
 so that a low voltage output from any one of the additional AND gate devices will result in the lowermost AND gate device producing a low voltage output. 
 
     
     
       4. A liquid level indicator as in  claim 3 
 wherein the lowermost electrical circuit further comprises an amplifier positioned between the AND gate device and the bi-color LED assembly, said amplifier having an electrical output; 
 said bi-color LED assembly having a first input leg electrically connected to the output of the amplifier and a second input leg electrically connected to the power source, 
 said first input leg being driven to a lower voltage when the input from the AND gate device is driven to a lower voltage, 
 to extinguish light of the first color from the LED assembly and produce light of the second color.